This invention relates to apparatus for manufacturing single-faced corrugated board.
In the past, it has been the usual practice to produce single-faced corrugated board by passing a core board between a pair of corrugated rolls arranged one above another to rotate in the opposite directions to corrugate the core board, applying a paste to the tops of the corrugations in the core board by a pasting roll while holding the core board in close contact with the bottom roll by guide fingers arranged along the lower half of the bottom roll and facing the pasted core board with a liner board fed by way of a separate press roll rotated in the opposite direction to the bottom roll while passing them between the bottom roll and the press roll. In this case, the guide fingers guide the core board along the bottom roll while preventing the core board from slipping off the bottom roll due to the resilience of the core board and the centrifugal force caused by the rotation of the bottom roll.
However, prior art single-faced corrugated board manufacturing apparatus of the type employing guide fingers to closely press a core board against the bottom roll, have the following disadvantages.
1. Due to the need to arrange both of the guide fingers and the pasting roll opposite to the lower half peripheral surface of the bottom roll, it is impossible to apply the paste to the portions of the core board corresponding to the guide fingers with the resulting deterioration of the strength of corrugated board boxes.
2. As the rotational speed increases, excepting the portions pressed by the guide fingers, the core board bulges due to the centrifugal force, thus deteriorating the application of paste and the formation of corrugations with the resulting reduction in the strength.
3. Due to the friction between the guide fingers and the core board, the corrugations get out of shape and the strength of the resulting corrugated board is decreased.
4. It is extremely difficult to arrange the guide fingers in a manner that the proper application of paste is not impeded and the core board is accurately guided along the bottom roll, and moreover not only a high degree of accuracy and skill are respectively required for the shape and mounting of the guide fingers but also considerable expenses and labor are required for the replacement of the worn fingers.